Handler for taps and clicks. 更多...
| import 语句： | import QtQuick |
| 继承： | SinglePointHandler |
TapHandler is a handler for taps on a touchscreen or clicks on a mouse.
Detection of a valid tap gesture depends on gesturePolicy . The default value is DragThreshold, which requires the press and release to be close together in both space and time. In this case, DragHandler is able to function using only a passive grab, and therefore does not interfere with event delivery to any other Items or Input Handlers. So the default gesturePolicy is useful when you want to modify behavior of an existing control or Item by adding a TapHandler with bindings and/or JavaScript callbacks.
Note that buttons (such as
QPushButton
) are often implemented not to care whether the press and release occur close together: if you press the button and then change your mind, you need to drag all the way off the edge of the button in order to cancel the click. For this use case, set the
gesturePolicy
to
TapHandler.ReleaseWithinBounds
.
import QtQuick Rectangle { id: button signal clicked property alias text: buttonLabel.text height: Math.max(Screen.pixelDensity * 7, buttonLabel.implicitHeight * 1.2) width: Math.max(Screen.pixelDensity * 11, buttonLabel.implicitWidth * 1.3) radius: 3 property color dark: Qt.darker(palette.button, 1.3) gradient: Gradient { GradientStop { position: 0.0; color: tapHandler.pressed ? dark : palette.button } GradientStop { position: 1.0; color: dark } } TapHandler { id: tapHandler gesturePolicy: TapHandler.ReleaseWithinBounds onTapped: button.clicked() } Text { id: buttonLabel text: "Click Me" color: palette.buttonText anchors.centerIn: parent } }
For multi-tap gestures (double-tap, triple-tap etc.), the distance moved must not exceed QStyleHints::mouseDoubleClickDistance () with mouse and QStyleHints::touchDoubleTapDistance () with touch, and the time between taps must not exceed QStyleHints::mouseDoubleClickInterval ().
另请参阅 MouseArea and Pointer Handlers Example .
|
acceptedButtons : flags |
The mouse buttons which can activate this Pointer Handler.
默认情况下，此特性被设为 Qt.LeftButton . It can be set to an OR combination of mouse buttons, and will ignore events from other buttons.
For example, a control could be made to respond to left and right clicks in different ways, with two handlers:
Item { TapHandler { onTapped: console.log("left clicked") } TapHandler { acceptedButtons: Qt.RightButton onTapped: console.log("right clicked") } }
注意： Tapping on a touchscreen or tapping the stylus on a graphics tablet emulates clicking the left mouse button. This behavior can be altered via acceptedDevices or acceptedPointerTypes .
|
acceptedDevices : flags |
The types of pointing devices that can activate this Pointer Handler.
默认情况下，此特性被设为 PointerDevice.AllDevices . If you set it to an OR combination of device types, it will ignore events from non-matching devices.
For example, a control could be made to respond to mouse and stylus clicks in one way, and touchscreen taps in another way, with two handlers:
Item { TapHandler { acceptedDevices: PointerDevice.Mouse | PointerDevice.Stylus onTapped: console.log("clicked") } TapHandler { acceptedDevices: PointerDevice.TouchScreen onTapped: console.log("tapped") } }
|
acceptedModifiers : flags |
If this property is set, it will require the given keyboard modifiers to be pressed in order to react to pointer events, and otherwise ignore them.
If this property is set to
Qt.KeyboardModifierMask
(the default value), then the
PointerHandler
ignores the modifier keys.
For example, an Item could have two handlers of the same type, one of which is enabled only if the required keyboard modifiers are pressed:
Item { TapHandler { acceptedModifiers: Qt.ControlModifier onTapped: console.log("control-tapped") } TapHandler { acceptedModifiers: Qt.NoModifier onTapped: console.log("tapped") } }
若设置
acceptedModifiers
to an OR combination of modifier keys, it means
all
of those modifiers must be pressed to activate the handler:
Item { TapHandler { acceptedModifiers: Qt.ControlModifier | Qt.AltModifier | Qt.ShiftModifier onTapped: console.log("control-alt-shift-tapped") } }
The available modifiers are as follows:
| 常量 | 描述 |
|---|---|
NoModifier
|
No modifier key is allowed. |
ShiftModifier
|
A Shift key on the keyboard must be pressed. |
ControlModifier
|
A Ctrl key on the keyboard must be pressed. |
AltModifier
|
An Alt key on the keyboard must be pressed. |
MetaModifier
|
A Meta key on the keyboard must be pressed. |
KeypadModifier
|
A keypad button must be pressed. |
GroupSwitchModifier
|
X11 only (unless activated on Windows by a command line argument). A Mode_switch key on the keyboard must be pressed. |
KeyboardModifierMask
|
The handler does not care which modifiers are pressed. |
If you need even more complex behavior than can be achieved with combinations of multiple handlers with multiple modifier flags, you can check the modifiers in JavaScript code:
Item { TapHandler { onTapped: switch (point.modifiers) { case Qt.ControlModifier | Qt.AltModifier: console.log("CTRL+ALT"); break; case Qt.ControlModifier | Qt.AltModifier | Qt.MetaModifier: console.log("CTRL+META+ALT"); break; default: console.log("other modifiers", point.modifiers); break; } } }
另请参阅 Qt::KeyboardModifier .
|
acceptedPointerTypes : flags |
The types of pointing instruments (finger, stylus, eraser, etc.) that can activate this Pointer Handler.
默认情况下，此特性被设为 PointerDevice.AllPointerTypes . If you set it to an OR combination of device types, it will ignore events from non-matching devices .
For example, a control could be made to respond to mouse, touch, and stylus clicks in some way, but delete itself if tapped with an eraser tool on a graphics tablet, with two handlers:
Rectangle { id: rect TapHandler { acceptedPointerTypes: PointerDevice.Generic | PointerDevice.Finger | PointerDevice.Pen onTapped: console.log("clicked") } TapHandler { acceptedPointerTypes: PointerDevice.Eraser onTapped: rect.destroy() } }
|
[read-only] active : bool |
This holds true whenever this Input Handler has taken sole responsibility for handing one or more eventPoints , by successfully taking an exclusive grab of those points. This means that it is keeping its properties up-to-date according to the movements of those eventPoints and actively manipulating its target (if any).
|
cursorShape : Qt::CursorShape |
This property holds the cursor shape that will appear whenever the mouse is hovering over the
parent
item while
active
is
true
.
The available cursor shapes are:
The default value is not set, which allows the cursor of parent item to appear. This property can be reset to the same initial condition by setting it to undefined.
注意：
When this property has not been set, or has been set to
undefined
, if you read the value it will return
Qt.ArrowCursor
.
另请参阅 Qt::CursorShape , QQuickItem::cursor ()，和 HoverHandler::cursorShape .
|
dragThreshold : int |
The distance in pixels that the user must drag an eventPoint in order to have it treated as a drag gesture.
The default value depends on the platform and screen resolution. It can be reset back to the default value by setting it to undefined. The behavior when a drag gesture begins varies in different handlers.
|
enabled : bool |
若 PointerHandler is disabled, it will reject all events and no signals will be emitted.
|
[since 6.5] exclusiveSignals : enumeration |
Determines the exclusivity of the singleTapped () 和 doubleTapped () 信号。
| 常量 | 描述 |
|---|---|
NotExclusive
|
(the default) singleTapped () 和 doubleTapped () are emitted immediately when the user taps once or twice, respectively. |
SingleTap
|
singleTapped () is emitted immediately when the user taps once, and doubleTapped () is never emitted. |
DoubleTap
|
doubleTapped () is emitted immediately when the user taps twice, and singleTapped () is never emitted. |
(SingleTap | DoubleTap)
|
Both signals are delayed until
QStyleHints::mouseDoubleClickInterval
(), such that either
singleTapped
() 或
doubleTapped
() can be emitted, but not both. But if 3 or more taps occur within
mouseDoubleClickInterval
, neither signal is emitted.
|
注意： The remaining signals such as tapped () 和 tapCountChanged () are always emitted immediately, regardless of this property.
该特性在 Qt 6.5 引入。
|
gesturePolicy : enumeration |
The spatial constraint for a tap or long press gesture to be recognized, in addition to the constraint that the release must occur before longPressThreshold has elapsed. If these constraints are not satisfied, the tapped signal is not emitted, and tapCount is not incremented. If the spatial constraint is violated, pressed transitions immediately from true to false, regardless of the time held.
The
gesturePolicy
also affects grab behavior as described below.
| 常量 | 描述 |
|---|---|
TapHandler.DragThreshold
Grab on press: passive |
(the default value) The
eventPoint
must not move significantly. If the mouse, finger or stylus moves past the system-wide drag threshold (
QStyleHints::startDragDistance
), the tap gesture is canceled, even if the device or finger is still pressed. This policy can be useful whenever
TapHandler
needs to cooperate with other input handlers (for example
DragHandler
) or event-handling Items (for example
Qt Quick Controls
), because in this case
TapHandler
will not take the exclusive grab, but merely a
passive grab
. That is,
DragThreshold
is especially useful to
augment
existing behavior: it reacts to tap/click/long-press even when another item or handler is already reacting, perhaps even in a different layer of the UI. The following snippet shows one
TapHandler
as used in one component; but if we stack up two instances of the component, you will see the handlers in both of them react simultaneously when a press occurs over both of them, because the passive grab does not stop event propagation:
Item { width : 120 ; height : 80 component Button : Rectangle { TapHandler { id : tapHandler gesturePolicy : TapHandler . DragThreshold // the default onTapped : tapFlash . start () } } Button { x : 10 ; y : 10 } Button { x : 30 ; y : 30 } } |
TapHandler.WithinBounds
Grab on press: exclusive |
若
eventPoint
leaves the bounds of the
parent
Item, the tap gesture is canceled. The
TapHandler
will take the
exclusive grab
on press, but will release the grab as soon as the boundary constraint is no longer satisfied.
TapHandler { id : tapHandler gesturePolicy : TapHandler . WithinBounds onTapped : tapFlash . start () } |
TapHandler.ReleaseWithinBounds
Grab on press: exclusive |
At the time of release (the mouse button is released or the finger is lifted), if the
eventPoint
is outside the bounds of the
parent
Item, a tap gesture is not recognized. This corresponds to typical behavior for button widgets: you can cancel a click by dragging outside the button, and you can also change your mind by dragging back inside the button before release. Note that it's necessary for
TapHandler
to take the
exclusive grab
on press and retain it until release in order to detect this gesture.
TapHandler { id : tapHandler gesturePolicy : TapHandler . ReleaseWithinBounds onTapped : tapFlash . start () } |
TapHandler.DragWithinBounds
Grab on press: exclusive |
On press,
TapHandler
takes the
exclusive grab
; after that, the
eventPoint
can be dragged within the bounds of the
parent
item, while the
timeHeld
property keeps counting, and the
longPressed
() signal will be emitted regardless of drag distance. However, like
WithinBounds
, if the point leaves the bounds, the tap gesture is
canceled
(),
active()
becomes
false
，和
timeHeld
stops counting. This is suitable for implementing press-drag-release components, such as menus, in which a single
TapHandler
detects press,
timeHeld
drives an "opening" animation, and then the user can drag to a menu item and release, while never leaving the bounds of the parent scene containing the menu. This value was added in Qt 6.3.
TapHandler { id : menuPopupHandler gesturePolicy : TapHandler . DragWithinBounds onPressedChanged : if ( pressed ) { menu . x = point . position . x - menu . width / 2 menu . y = point . position . y - menu . height / 2 } else { feedback . text = menu . highlightedMenuItem selectFlash . start () } onCanceled : feedback . text = "canceled" } |
The Pointer Handlers Example demonstrates some use cases for these.
注意：
If you find that
TapHandler
is reacting in cases that conflict with some other behavior, the first thing you should try is to think about which
gesturePolicy
is appropriate. If you cannot fix it by changing
gesturePolicy
, some cases are better served by adjusting
grabPermissions
, either in this handler, or in another handler that should
prevent
TapHandler
from reacting.
|
grabPermissions : flags |
This property specifies the permissions when this handler's logic decides to take over the exclusive grab, or when it is asked to approve grab takeover or cancellation by another handler.
| 常量 | 描述 |
|---|---|
PointerHandler.TakeOverForbidden
|
This handler neither takes from nor gives grab permission to any type of Item or Handler. |
PointerHandler.CanTakeOverFromHandlersOfSameType
|
This handler can take the exclusive grab from another handler of the same class. |
PointerHandler.CanTakeOverFromHandlersOfDifferentType
|
This handler can take the exclusive grab from any kind of handler. |
PointerHandler.CanTakeOverFromItems
|
This handler can take the exclusive grab from any type of Item. |
PointerHandler.CanTakeOverFromAnything
|
This handler can take the exclusive grab from any type of Item or Handler. |
PointerHandler.ApprovesTakeOverByHandlersOfSameType
|
This handler gives permission for another handler of the same class to take the grab. |
PointerHandler.ApprovesTakeOverByHandlersOfDifferentType
|
This handler gives permission for any kind of handler to take the grab. |
PointerHandler.ApprovesTakeOverByItems
|
This handler gives permission for any kind of Item to take the grab. |
PointerHandler.ApprovesCancellation
|
This handler will allow its grab to be set to null. |
PointerHandler.ApprovesTakeOverByAnything
|
This handler gives permission for any type of Item or Handler to take the grab. |
默认为
PointerHandler.CanTakeOverFromItems | PointerHandler.CanTakeOverFromHandlersOfDifferentType | PointerHandler.ApprovesTakeOverByAnything
which allows most takeover scenarios but avoids e.g. two PinchHandlers fighting over the same touchpoints.
|
longPressThreshold : real |
The time in seconds that an eventPoint must be pressed in order to trigger a long press gesture and emit the longPressed () signal. If the point is released before this time limit, a tap can be detected if the gesturePolicy constraint is satisfied. The default value is QStyleHints::mousePressAndHoldInterval () converted to seconds.
|
margin : real |
The margin beyond the bounds of the
parent
item within which an
eventPoint
can activate this handler. For example, on a
PinchHandler
在哪里
target
is also the
parent
, it's useful to set this to a distance at least half the width of a typical user's finger, so that if the
parent
has been scaled down to a very small size, the pinch gesture is still possible. Or, if a
TapHandler
-based button is placed near the screen edge, it can be used to comply with Fitts's Law: react to mouse clicks at the screen edge even though the button is visually spaced away from the edge by a few pixels.
默认值为 0。
|
parent : Item |
The Item which is the scope of the handler; the Item in which it was declared. The handler will handle events on behalf of this Item, which means a pointer event is relevant if at least one of its eventPoints occurs within the Item's interior. Initially target() is the same, but it can be reassigned.
注意：
When a handler is declared in a
QtQuick3D.Model
object, the parent is not an Item, therefore this property is
null
.
另请参阅 target and QObject::parent ().
|
[read-only] point : handlerPoint |
The eventPoint currently being handled. When no point is currently being handled, this object is reset to default values (all coordinates are 0).
|
[read-only] pressed : bool |
Holds true whenever the mouse or touch point is pressed, and any movement since the press is compliant with the current gesturePolicy . When the eventPoint is released or the policy is violated, pressed will change to false.
|
[read-only] tapCount : int |
The number of taps which have occurred within the time and space constraints to be considered a single gesture. The counter is reset to 1 if the button changed. For example, to detect a triple-tap, you can write:
Rectangle { width: 100; height: 30 signal tripleTap TapHandler { acceptedButtons: Qt.AllButtons onTapped: if (tapCount == 3) tripleTap() } }
|
target : Item |
The Item which this handler will manipulate.
By default, it is the same as the
parent
, the Item within which the handler is declared. However, it can sometimes be useful to set the target to a different Item, in order to handle events within one item but manipulate another; or to
null
, to disable the default behavior and do something else instead.
|
[read-only] timeHeld : real |
The amount of time in seconds that a pressed point has been held, without moving beyond the drag threshold. It will be updated at least once per frame rendered, which enables rendering an animation showing the progress towards an action which will be triggered by a long-press. It is also possible to trigger one of a series of actions depending on how long the press is held.
A value of less than zero means no point is being held within this handler's Item .
注意：
若
gesturePolicy
被设为
TapHandler.DragWithinBounds
,
timeHeld
does not stop counting even when the pressed point is moved beyond the drag threshold, but only when the point leaves the
parent
item's
bounds
.
|
canceled ( eventPoint point ) |
If this handler has already grabbed the given point , this signal is emitted when the grab is stolen by a different Pointer Handler or Item.
注意：
相应处理程序是
onCanceled
.
|
doubleTapped ( eventPoint eventPoint , Qt::MouseButton button ) |
此信号被发射当
parent
Item is tapped twice within a short span of time (
QStyleHints::mouseDoubleClickInterval
()) and distance (
QStyleHints::mouseDoubleClickDistance
() 或
QStyleHints::touchDoubleTapDistance
()). This signal always occurs after
singleTapped
,
tapped
，和
tapCountChanged
。
eventPoint
signal parameter contains information from the release event about the point that was tapped, and
button
是
mouse button
that was clicked, or
NoButton
on a touchscreen.
注意：
相应处理程序是
onDoubleTapped
.
|
grabChanged ( PointerDevice::GrabTransition transition , eventPoint point ) |
This signal is emitted when the grab has changed in some way which is relevant to this handler.
The transition (verb) tells what happened. The point (object) is the point that was grabbed or ungrabbed.
注意：
相应处理程序是
onGrabChanged
.
|
longPressed () |
此信号被发射当
parent
Item is pressed and held for a time period greater than
longPressThreshold
. That is, if you press and hold a touchpoint or button, while any movement does not exceed the drag threshold, then the
longPressed
signal will be emitted at the time that
timeHeld
exceeds
longPressThreshold
.
注意：
相应处理程序是
onLongPressed
.
|
singleTapped ( eventPoint eventPoint , Qt::MouseButton button ) |
此信号被发射当
parent
Item is tapped once. After an amount of time greater than
QStyleHints::mouseDoubleClickInterval
, it can be tapped again; but if the time until the next tap is less,
tapCount
will increase. The
eventPoint
signal parameter contains information from the release event about the point that was tapped, and
button
是
mouse button
that was clicked, or
NoButton
on a touchscreen.
注意：
相应处理程序是
onSingleTapped
.
|
tapCountChanged () |
此信号被发射当
parent
Item is tapped once or more (within a specified time and distance span) and when the present
tapCount
differs from the previous
tapCount
.
注意：
相应处理程序是
onTapCountChanged
.
|
tapped ( eventPoint eventPoint , Qt::MouseButton button ) |
This signal is emitted each time the
parent
Item is tapped.
That is, if you press and release a touchpoint or button within a time period less than
longPressThreshold
, while any movement does not exceed the drag threshold, then the
tapped
signal will be emitted at the time of release. The
eventPoint
signal parameter contains information from the release event about the point that was tapped, and
button
是
mouse button
that was clicked, or
NoButton
on a touchscreen.
import QtQuick Rectangle { width: 100 height: 100 TapHandler { acceptedButtons: Qt.LeftButton | Qt.RightButton onTapped: (eventPoint, button)=> console.log("tapped", eventPoint.device.name, "button", button, "@", eventPoint.scenePosition) } }
注意：
相应处理程序是
onTapped
.
